液体对钢轨滚动接触疲劳裂纹的作用

Effect of Liquid on Rolling Contact Fatigue Cracks in Rail

摘要:

建立基于耦合欧拉-拉格朗日方法的液体-裂纹流固耦合数值模型，分析移动轮轨接触荷载下液体对钢轨滚动接触疲劳裂纹面之间的压力分布情况，研究了不同黏度液体对不同长度、不同角度裂纹的作用。结论发现：高黏度液体对裂纹全长均有压力，对裂纹面的压力是低黏度液体压力的4.8 ~ 5.9倍，且越靠近裂纹尖端的压力越大，算例工况下脂类对裂纹尖端的压力最大值达到约690 ~ 751MPa。随着接触荷载通过裂纹开口，高黏度液体仍然停留在裂纹内，对裂纹面压力作用持续时间较长，约占一次荷载周期的80% ~ 90%，在一个荷载周期内对裂纹面的压力分布呈马鞍状。而低黏度液体会随着轮轨接触荷载的运行被挤出裂纹，主要对裂纹开口及中段形成较大压力，对裂纹面的压力作用持续时间仅占一次荷载周期的10% ~ 30%，在一个荷载周期内对裂纹面的压力分布呈山峰状。裂纹角度越大、长度越长，液体对裂纹面的压力作用更大，裂纹扩展趋势更明显。裂纹角度为30°和40°时分别较20°时，高黏度液体对裂纹面压力最大值增大了38.5% ~ 63.8%和1.1~ 1.2倍。裂纹长度为2mm时较1.5mm时，高黏度液体对裂纹面压力最大值增大了6.1% ~ 8.3%。

Abstract:

A fluid-solid coupling numerical model considering the liquid and rolling contact fatigue （RCF） crack in rail based on the Coupled Euler-Lagrangian （CEL） method was established. The pressure distribution by the liquid on the crack internal surface under moving wheel-rail contact load was analyzed. The effect of the liquid with different viscosities on the RCF cracks with different lengths and propagation angles was researched. The conclusions show that the pressure by the high-viscosity liquid （HL） distributed on the entire length of the crack which was 4.8~5.9 times than that of the low-viscosity liquid （LL）. The closer to the crack tip， the greater the pressure generated by HL. And the maximum pressure on the crack tip reached about 690~751MPa in the example. With the wheel load passing the crack mouth， the HL still kept in the crack and the pressure by it on the crack surface lasted for a long time， about 80%~ 90% of a load cycle， with saddle-shaped pressure distribution on the crack surface. While the LL was extruded from the crack by the passing load which made the pressure mainly on the mouth and middle part of the crack for a short time， about 10%~30% of a load cycle， with peak-shaped pressure distribution on the crack surface. The larger the crack angle and the longer the crack length were， the more pressure on crack surface was and the easier the crack would propagate. When the crack angle was 30° and 40°， the hydraulic pressure by HL increased about 38.5%~63.8% and 1.1~1.2 times respectively compared to that of the crack angle with 20°. The maximum pressure by HL with 2.0 mm length was increased about 6.1%~8.3% than that of with 1.5 mm length.